diff --git a/cypress/platform/css1.html b/cypress/platform/css1.html
index efb37a53a..f02892123 100644
--- a/cypress/platform/css1.html
+++ b/cypress/platform/css1.html
@@ -12,11 +12,22 @@
   </style>
 </head>
 <body>
-  <div class="mermaid">
+  <div class="mermaid2">
   %%{init: { 'themeCSS': '} * { background: lightblue }' } }%%
   flowchart TD
     a --> b
   </div>
+  <div class="mermaid">
+   %%{init:{"theme":"base", "themeVariables": {"primaryColor":"#411d4e", "titleColor":"white", "darkMode":true}}}%%
+    flowchart LR
+    subgraph A
+        a --> b
+    end
+    subgraph B
+        i -->f
+    end
+    A --> B
+  </div>
   <script src="./mermaid.js"></script>
   <script>
      function showFullFirstSquad(elemName) {
diff --git a/src/defaultConfig.js b/src/defaultConfig.js
index 92d8b5771..305ba0867 100644
--- a/src/defaultConfig.js
+++ b/src/defaultConfig.js
@@ -37,6 +37,7 @@ const config = {
   themeCSS: undefined,
   /* **maxTextSize** - The maximum allowed size of the users text diamgram */
   maxTextSize: 50000,
+  darkMode: false,
 
   /**
    * | Parameter  | Description                                            | Type   | Required | Values                      |
